CN110663271B

CN110663271B - Method and apparatus for transmitting system information in a synchronization signal block

Info

Publication number: CN110663271B
Application number: CN201880033912.5A
Authority: CN
Inventors: A.格罗夫伦; H.萨林; 汪剑锋
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2017-03-24
Filing date: 2018-03-21
Publication date: 2021-11-19
Anticipated expiration: 2038-03-21
Also published as: EP3749021A1; EP3459289B1; US20240048426A1; MX2019011200A; US10476722B2; EP3459289A1; EP3749021B1; ES2922226T3; JP7061210B2; US20200014571A1; EP4102794A1; JP6832447B2; JP2021090201A; WO2018174796A1; JP2020515196A; PH12019502159A1; CA3057584A1; US20210126821A1; US20190123951A1; CN114071447A

Abstract

The present disclosure relates to a method performed by a wireless device for receiving system information from a network node of a wireless communication system. System information is received in a Synchronization Signal (SS) block of a set of SS bursts that includes the SS block. The system information is multiplexed with information that provides a time index that indicates which SS block of the set of SS bursts is being received. The method comprises the following steps: receiving (410) information providing a time index, and receiving (430) system information, the receiving system information comprising descrambling the system information using a scrambling sequence generated (420) based on the information providing the time index. The method further comprises the following steps: the accuracy of the information providing the time index is determined (440) based on an error detection code associated with the received system information. The disclosure also relates to corresponding network node methods and devices.

Description

Method and apparatus for transmitting system information in a synchronization signal block

Technical Field

The present invention relates to: a method for transmitting system information in a synchronization signal block, and a wireless device, a network node, a computer program and a computer program device.

Background

Fifth generation (5G) mobile telecommunications and wireless technologies have not been fully defined, but are in the advanced draft stage within the third generation partnership project (3 GPP). It includes work on the 5G New Radio (NR) access technology. Long Term Evolution (LTE) technology terminology is used in a prospective sense in this disclosure to include equivalent 5G entities or functionality, although different terms are specified in 5G. A general description of the agreement so far regarding the physical layer aspects of the 5G NR access technology is contained in the 3GPP technical report 38.802 v1.2.0 (2017-02). Furthermore, the final specifications may be published in the future 3GPP TS 38.2 series.

Fig. 1 schematically illustrates a wireless communication network in which a user equipment UE1 is capable of wirelessly connecting to a base station BS 2. The BS 2 is connected to a core network CN 3. In NR access networks, the BS may be referred to as a gNB, and the corresponding technical term for LTE access networks is eNB. The BS 2 serves the UE1 located within the geographic service area (referred to as a cell) of the BS.

Initial access and synchronization in cellular systems

When a wireless device (or UE) first accesses a wireless communication system, it must synchronize to the system. The UE needs synchronization to know when the network will transmit various signals, such as broadcast of System Information (SI). The UE must also synchronize to the system to know when it should transmit uplink signals, such as random access signals transmitted during initial access.

Wireless communication systems use different units of time to track time. In systems using Orthogonal Frequency Division Multiplexing (OFDM), the term OFDM symbol is used for the smallest unit of time. Several symbols may form a slot, several slots may form a subframe, and several subframes may form a radio frame. The system information and paging information are typically distributed over a time scale of time units for which radio frames are relevant. In many cellular system standards, the radio frame is 10 ms.

In LTE, there are two synchronization signals: primary Synchronization Signals (PSS) and Secondary Synchronization Signals (SSS). In order to perform initial access, the UE must obtain at least symbol synchronization and frame synchronization. To obtain symbol synchronization, the UE searches for a special synchronization sequence, which corresponds to the PSS. PSS is typically one symbol long. By finding this sequence, the UE can establish the symbol timing. The UE may also determine frame synchronization using the received PSS. In order to make this possible, each PSS must be transmitted with a fixed timing relationship to the start of the frame. When the UE has found the PSS, it can also read the identifier of the current cell and very basic system information called the Master Information Block (MIB). Thus, in addition to providing synchronized functionality, the PSS and SSS are used to indicate the physical layer cell identity (PCI) to the UE.

In NR, the concepts of PSS and SSS are reused to provide initial synchronization and are referred to as NR-PSS and NR-SSS. NR-PSS is defined for initial symbol boundary synchronization to NR cells. NR-SSS is defined for detecting at least part of NR cell identity (cell ID) or NR cell ID.

In NR, a broadcast channel called NR physical broadcast channel (NR-PBCH) is defined. The NR-PBCH is a non-scheduled broadcast channel that carries a portion of minimum system information with a periodicity that is predefined in the specification according to a carrier frequency range and a fixed payload size. The NR-PBCH content should include at least part of the System Frame Number (SFN) and a Cyclic Redundancy Check (CRC). The following is a list of options that the NR-PBCH can carry in terms of system information:

option 1: the NR-PBCH carries a portion of necessary system information for initial access, the portion including information necessary for the UE to receive channels carrying remaining necessary system information;

option 2: in addition to the information that initial access is allowed in option 1, the NR-PBCH carries minimum information necessary for the UE to perform initial UL transmission; and

option 3: the NR-PBCH carries all necessary system information for initial access.

In NR, it would be possible to transmit NR-PSS using beamforming. The NR-PSS will be transmitted in different beams at different time instants. The beam through which the NR-PSS is transmitted is selected such that a UE anywhere in the cell can receive at least one NR-PSS transmission. Sometimes the term beam scanning is used for this process. To support the beam scanning of the NR-PSS, more than one NR-PSS must be transmitted in each frame, otherwise the synchronization delay will be too long. This means that the NR-PSS transmitted in different beams will have different offsets with respect to the frame start, which in turn means that the UE cannot derive the frame start from only the time it received the NR-PSS. Some additional information is required.

To support beam scanning for massive multiple-input multiple-output (MIMO), a new concept of SS block has been defined to include some basic signals and broadcast system information. The NR-PSS, NR-SSS and/or NR-PBCH can be transmitted within an SS block. However, multiplexing other signals within the SS block is not excluded. The UE should be able to identify the radio frame number, slot index in the radio frame, and OFDM symbol index from the SS block.

In the 3GPP agreement for NR, a basic structure for synchronization signals and channels has been defined. Fig. 2b shows a schematic diagram of the basic structure for synchronization signal transmission. One or more SS blocks constitute an SS burst. The one or more SS bursts further comprise a set of SS bursts, wherein the number of SS bursts within the set of SS bursts is limited. In the example illustrated in fig. 2b, the number of SS block(s) constituting one SS burst set is L, where L is a positive integer. From the perspective of physical layer specifications, at least one period of the set of SS bursts is supported. From the UE perspective, the SS burst set transmission is periodic, and the UE may assume that a given SS block is repeated with an SS burst set period.

3GPP has decided that there can be as many as 64 SS blocks in an SS burst set. The minimum period for the set of SS blocks is 5ms and the radio frame is 10 ms. Thus, the number of SS blocks in a radio frame can be as high as 128.

Disclosure of Invention

Synchronization signals (including NR-PSS and NR-SSS) would thus be included in the SS blocks, and the terminal or UE is expected to acquire downlink synchronization via successful detection of the SS blocks. As indicated above, it is also considered that part of the system information is delivered in the NR-PBCH, which is also included in the SS block.

NR-PSS, NR-SSS and NR-PBCH (i.e., Time Division Multiplexing (TDM) of NR-PSS, NR-SSS and NR-PBCH) have been agreed to be multiplexed in the time domain in SS blocks.

In order to indicate the boundaries of SS bursts and/or sets of SS bursts through SS block detection, a time index should be provided from the SS block detection. In other words, the time index may indicate which SS block of an SS burst or set of SS bursts has been detected, and/or which SS burst of a set of SS bursts has been detected. Different ways of providing time indexing have been discussed in several 3GPP contributions. An additional so-called synchronization signal in the SS block, called NR third synchronization signal (NR-TSS), is one solution that has been discussed. The NR-TSS provides a time index of the SS burst or SS block in the set of SS bursts. Fig. 2a schematically illustrates an exemplary embodiment of an SS block comprising the following multiplexed in the SS block: system information of NR-PBCH, NR-TSS payload or bits, and NR-PSS and NR-SSS, the SS block having a certain SS block bandwidth in the frequency dimension and an SS block size of four OFDM symbols in the time dimension. Thus, the time index provided by the NR-TSS can be used by the UE to determine: where the boundary of an SS burst or set of SS bursts is, or where an SS burst or set of SS bursts starts. In one exemplary scenario, there may be up to 128 SS blocks in an SS burst or set of SS bursts. To provide a time index indicating the boundary of an SS burst or set of SS bursts in this exemplary scenario, the NR-TSS must include at least seven bits.

Since the number of bits of the NR-TSS may not be very large, e.g., less than ten bits, CRC attachment on the codeword of the NR-TSS may introduce significant overhead. Therefore, it has been considered that: NR-TSS is delivered without CRC addition. However, this will lead to the following problems:

the UE does not know whether the detection of NR-TSS is correct;

if the NR-TSS is detected erroneously, the system information delivered in the NR-PBCH of the SS block (which is e.g. required to be able to perform random access) cannot be decoded correctly, because the time index indicating the boundary of the SS burst or set of SS bursts is incorrect;

this in turn can lead to delays for receiving system information and performing random access or initial access procedures.

It is therefore an object to address some of the problems outlined above and to provide a solution that makes the following aspects possible: the terminal or UE knows as soon as possible whether the detected or received value of the time index, e.g. derived from the NR-TSS, is correct or not in order to avoid unnecessary overhead and delay with respect to the initial access procedure.

According to a first aspect, a method performed by a wireless device for receiving system information from a network node of a wireless communication system is provided. The system information is received in an SS block of a set of SS bursts that includes at least one synchronization signal SS block. The system information is multiplexed with information that provides a time index that indicates which SS block of the set of SS bursts is being received. The method includes receiving information providing a time index. The method further includes receiving system information, wherein receiving includes descrambling the system information using a scrambling sequence generated based on the information providing the time index. The method further comprises the following steps: the accuracy of the information providing the time index is determined based on an error detection code associated with the received system information.

According to a second aspect, there is provided a method performed by a network node of a wireless communication network for transmitting system information to a wireless device in an SS block of a set of SS bursts comprising at least one synchronization signal SS block. The system information is multiplexed with information that provides a time index that indicates which SS block of the set of SS bursts is being transmitted. The method includes scrambling system information using a scrambling sequence generated based on information providing a time index, and transmitting the scrambled system information multiplexed with the information providing the time index of the SS block to a wireless device, wherein an error detection code is associated with the system information.

According to further aspects, a wireless device, a network node, a computer program and a computer program product according to the appended claims are provided.

In general, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the element, device, component, means, step, etc" are to be interpreted openly as referring to at least one instance of the element, device, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Other objects, advantages and features of the embodiments will be explained in the following detailed description when considered in conjunction with the drawings and claims.

Drawings

The invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram illustrating an environment in which embodiments presented herein can be applied;

FIG. 2a is a schematic diagram of an example of an SS block including NR-TSS;

fig. 2b is a schematic diagram illustrating SS blocks and sets of SS bursts;

figure 2c is a flow chart of the NR-PBCH scrambling process and a graphical representation of the resulting scrambled bits and symbols;

fig. 3 is a flow chart illustrating a method in a network node according to an embodiment.

Fig. 4 is a flow chart illustrating a method in a wireless device according to an embodiment.

Fig. 5 is a block diagram schematically illustrating a network node according to an embodiment.

Fig. 6 is a block diagram schematically illustrating a wireless device according to an embodiment.

Fig. 7 is a signaling diagram schematically illustrating an embodiment of a method performed in a UE or wireless device 600 and a BS or network node 500, such as the UE and the gNB of an NR system.

Detailed Description

In the following, different aspects will be described in more detail with reference to certain embodiments and the accompanying drawings. For purposes of explanation and not limitation, specific details are set forth, such as particular scenarios and techniques, in order to provide a thorough understanding of the different embodiments. However, other embodiments that depart from these details are also possible.

Moreover, in some instances, detailed descriptions of well-known methods, nodes, interfaces, circuits, and devices are omitted so as not to obscure the description with unnecessary detail. Those skilled in the art will recognize that the described functionality may be implemented in one node or in several nodes. Some or all of the described functions may be implemented using hardware circuitry, such as analog and/or discrete logic gates interconnected to perform the specified functions, or an ASIC. Also, some or all of the functions may be implemented using software programs and data in conjunction with one or more digital microprocessors or general purpose computers. Where nodes are described which communicate using the air interface, it will be appreciated that those nodes also have suitable radio communications circuitry. Moreover, the techniques may be fully embodied within any form of computer readable memory, including non-transitory embodiments, such as solid-state memory, magnetic disk, or optical disk containing an appropriate set of computer instructions or computer program code that would cause a processor to perform the techniques described herein.

A hardware implementation of the invention can include, without limitation, Digital Signal Processor (DSP) hardware, reduced instruction set processor(s), hardware (e.g., digital or analog) circuitry including, without limitation, application specific integrated circuit(s) (ASIC) and/or field programmable gate array(s) (FPGA), and, where appropriate, a state machine capable of performing such functions.

In computer-implemented aspects, a computer is generally understood to include one or more processors or one or more controllers, and the terms computer, processor, and controller may be used interchangeably. When provided by a computer, processor, or controller, the functions may be provided by a single dedicated computer or processor or controller, by a single shared computer or processor or controller, or by a plurality of separate computers or processors or controllers, some of which may be shared or distributed. Moreover, the term "processor" or "controller" also refers to other hardware capable of performing such functions and/or executing software, such as the exemplary hardware set forth above.

Herein, the terms User Equipment (UE), terminal and wireless device are used interchangeably to refer to a device that communicates with a network infrastructure, a wireless communication network or a radio access network. The term should not be construed to mean any particular type of device, i.e. it applies to all of them, and the embodiments described herein may be applied to all devices using the relevant solutions to solve the described problems. A wireless device is referred to as a UE in 3GPP technical terminology and may include, for example, a cellular telephone, a personal digital assistant, a smartphone, a laptop, a handheld computer, a machine type communication/machine to machine (MTC/M2M) device, or other device or terminal having wireless communication capabilities. A wireless device may refer to a terminal installed in a fixed configuration, such as in some machine-to-machine applications, and may refer to a portable device, or a device installed in a motor vehicle.

Similarly, a network node is intended to mean a node in the network infrastructure that communicates with the UE, sometimes referred to as a Base Station (BS). Different names may be applicable, such as eNB and gNB, depending on the radio access technology. The functionality of the network nodes may be distributed in various ways. For example, there may be a radio head terminating a portion of the radio protocol and a centralized unit terminating other portions of the radio protocol. The term "network node" will refer to all alternative architectures that can implement the related invention, and no distinction will be made between such implementations.

Embodiments are described in a non-limiting general context related to an exemplary scenario in an NR wireless communication network or system, such as the network illustrated in fig. 1, where a gNB (BS 2) sends system information to a UE1 in an SS block of a set of SS bursts, where the SS block includes NR-TSS, i.e., information that provides a time index of the SS block. The information providing the time index may not have any error detection code (such as a CRC) attached to it. It should be noted, however, that in embodiments, the information providing the time index of the SS block may correspond to another type of signal other than NR-TSS, and that these embodiments may be applied to any wireless communication network that achieves network synchronization by transmitting multiple SS blocks in a set of SS bursts as previously described.

The problem of delay associated with the process of receiving system information and performing initial access, which is introduced due to an error in the NR-TSS of a received SS block, is solved by a solution of: this solution allows to check the accuracy or reliability of the received NR-TSS early in the initial access procedure by a scheme that includes scrambling the system information of the NR-PBCH with a scrambling code or sequence generated by the time index indicated or provided by the NR-TSS.

In one embodiment, the encoded bits of the system information are scrambled, for example, by: each bit is multiplied element-by-element by a pseudo-random sequence, which is generated based on information providing a time index. The pseudo-random sequence may also optionally be generated based on the cell ID alone or in combination with some other parameter or value received in the SS block.

In another embodiment, scrambling is performed at the modulation symbol level, for example, by: each Quadrature Phase Shift Keying (QPSK) symbol of the system information of the NR-PBCH is element-wise multiplied by a pseudo-random sequence, which can be generated as described above.

Some advantages of embodiments of the invention are that delays and unnecessary transmissions that may occur due to erroneous detection of the NR-TSS and thus also incorrect time index values can be avoided.

Scrambling sequence generation

In one exemplary embodiment, the sequence used to scramble the signal may be a pseudo-random sequence, which may be flexibly selected. Using the sequence defined in LTE as an example, a Gold sequence of length 31 is defined as a pseudo-random sequence, length

Output sequence of

(wherein

) Defined by the following equation:

wherein

. Should use

To initialize the first m-sequence. Initialization of the second m-sequence is performed by

Indicating that the value depends on the application of the sequence.

For NR-PBCH transmissions (such as system information transmissions), the scrambling sequence may be initialized at the beginning of each SS block, SS burst, or set of SS bursts. Correspond to

Depends on the time index derived from the NR-TSS and optionally also on the cell ID and other values (such as SFN) that may be needed for generating the sequence. For example, the value can be defined according to the following equation:

，

wherein

Is the SS block time index to be delivered or provided by the NR-TSS, and

is the cell ID, which is delivered by the NR-SSS and NR-PSS in the same SS block.xMay be considered as other information that may be delivered in the NR-PBCH in embodiments of the present invention, such as SFN.

Scrambling NR-PBCH information with generated sequences

Once the scrambling sequence has been generated, the scrambling process of the information carried by the NR-PBCH can be started. The scrambling process of the information may be performed at different levels, as illustrated in fig. 2 c. The flow chart on the left side of fig. 2c shows the process step by step, while the resulting bits or symbols are shown on the right side. The process starts with information bits 200 corresponding to the system information of the NR-PBCH. At 240, the CRC is appended, resulting in information bits with CRC attachment 210. In a first embodiment, illustrated in step 241, the CRC bits are the only scrambled bits, the resulting scrambled CRC bits being shown in 215. Scrambling may be performed at this level, i.e. only the CRC bits of the NR-PBCH transport block are scrambled. In such embodiments, the receiving wireless device or UE receives the NR-PBCH information with the scrambled CRC. The UE also generates a scrambling sequence based on the time index it has received in the SS block and can thus use the scrambling sequence to descramble the CRC bits. After descrambling, the UE may perform CRC check on the system information of the NR-PBCH received according to the time index provided by the NR-TSS. If the CRC check indicates erroneously received system information, this may be due to: the NR-TSS has been incorrectly detected or received and thus provides an incorrect time index value, or the reception of the system information of the NR-PBCH is itself incorrect. In either case, the subsequent initial access procedure is stopped as soon as the CRC check indicates an error, thereby avoiding unnecessary delays. It is then possible to detect a new SS block, which can provide the correct system information. Correctly received system information will eventually make it possible to perform a complete initial access procedure.

In the second embodiment, the channel coding and the rate matching in 242 are performed on the information bits with the CRC bits attached. As described above, the appended CRC bits may be scrambled 215, but they may also be unscrambled. This results in encoded bits 220. Bit level scrambling at 243 may be performed on the encoded bits 220, resulting in scrambled encoded bits 225. In this embodiment, the network node would scramble all encoded bits using a scrambling sequence. If the scrambling sequence is erroneously generated by the wireless device due to an erroneous value of the time index provided by the NR-TSS, the CRC check of the wireless device at the receiving side will indicate this. The wireless device can thus infer: the NR-TSS providing the time index is incorrect, or the system information is incorrect, similar to the previous example of scrambling only CRC bits.

Whether or not the coded bits have been scrambled, they may undergo modulation in 244, resulting in modulated symbols 230. In a third embodiment, the modulated symbols may undergo symbol level scrambling at 245, resulting in scrambled modulated symbols 235. In this embodiment, the CRC check performed by the receiving wireless device for the NR-PBCH system information indicates whether the received time index is accurate. As indicated above, the first, second and third embodiments involving scrambling at different levels can be implemented in any combination or independently of each other. Common to all of them is that the time index provided from the NR-TSS is involved in each scrambling procedure, as it is used to generate the scrambling sequence. The same or different scrambling sequences may be used for scrambling at different levels.

Embodiments of the method described with reference to fig. 3-4 and 7

Fig. 7 is a signaling diagram schematically illustrating an embodiment of a method performed in a UE or wireless device 600 and a BS or network node 500, such as the UE and the gNB of an NR system. The BS 500 broadcasts SS blocks in a set of SS bursts in a cell. When beam scanning is used, as explained in the background section, each SS block of a set of SS bursts is transmitted in a respective beam at a respective instant of a radio frame, as shown in fig. 2 b. A certain UE in the cell will thus receive at least one of the SS blocks, including the NR-PSS, NR-SSs and NR-PBCH carrying system information multiplexed with information providing the time index. The time index indicates which SS block of the set of SS bursts is being received. The UE needs this information to be able to synchronize to the network. As previously described, based on the information providing the time index, the network node generates 310 a scrambling sequence and scrambles 320 the system information bits. The network node then transmits 330 the SS block comprising scrambled system information multiplexed with the information providing the time index. The UE receives 410 the SS block including the information providing the time index and generates 420 a scrambling sequence based on the information providing the time index. The scrambling sequence is used to receive 430 and descramble system information. Using the error detection code appended to the system information, the UE can then determine 440 the accuracy of the information providing the time index. If the error detection code indicates erroneously received system information, the UE may assume that the information providing the time index is inaccurate.

Fig. 3 is a flow diagram illustrating one embodiment of a method performed by a network node of a wireless communication network for conveying system information to a wireless device in an SS block of a set of SS bursts comprising at least one synchronization signal SS block. In one embodiment, the wireless device is a UE and the network node is a nodeb. The system information is multiplexed with information that provides a time index that indicates which SS block of the set of SS bursts is being transmitted. Information providing a time index can be transmitted without any associated error detection codes. The method comprises the following steps:

-320: the system information is scrambled using a scrambling sequence generated 310 based on the information providing the time index. In an embodiment, the scrambling system information comprises encoded bits of the scrambling system information, as described above. However, scrambling can be performed at different levels. Scrambling system information may thus comprise at least one of: scrambling error detection code bits related to system information; scrambling encoded bits of system information; and scrambling the modulated symbols of the system information. Generating 310 the scrambling sequence may include initializing the scrambling sequence at the beginning of the SS block. Further, the scrambling sequence may be a pseudo-random sequence generated based on an identification (cell ID) of a cell (i.e., a cell in which the SS block is broadcast) associated with the SS block. In other exemplary embodiments, the scrambling sequence may be a pseudo-random sequence whose initialization value depends on the time index. The initialization value may depend on further parameters provided by the information carried by the SS block, such as cell ID or SFN.

-330: transmitting, to the wireless device, scrambled system information multiplexed with information providing a time index of the SS block, wherein the error detection code is associated with the system information. The error detection code may be a cyclic redundancy check, CRC, attachment to the information bits corresponding to the system information.

In an embodiment, SS blocks have a size in the time dimension during which synchronization signals (e.g., NR-PSS and NR-SSs), information providing time index (in one embodiment NR-TSS in SS blocks), and system information (in NR-PBCH) are transmitted.

Fig. 4 is a flow diagram illustrating one embodiment of a method performed by a wireless device for receiving system information from a network node of a wireless communication system, the system information being received in an SS block of a set of SS bursts comprising at least one SS block. In one embodiment, the wireless device is a UE and the network node is a nodeb. The system information is multiplexed with information that provides a time index that indicates which SS block of the set of SS bursts is being received. The information providing the time index may be received without any associated error detection codes. The method comprises the following steps:

-410: information providing a time index is received.

-430: system information is received, wherein receiving includes descrambling the system information using a scrambling sequence generated 420 based on information providing a time index. The descrambling system information may comprise encoded bits of the descrambling system information. However, descrambling the received system information may include at least one of the following as described above: descrambling bits of an error detection code associated with the system information; descrambling encoded bits of system information; and descrambling the modulated symbols of the system information. Generating 420 the scrambling sequence may include initializing the scrambling sequence at the beginning of the SS block. The scrambling sequence may be a pseudo-random sequence generated based on the identity of the cell (cell ID) associated with the SS block. In an embodiment, the scrambling sequence may be a pseudo-random sequence whose initialization value depends on the time index. Further, the initialization value may depend on further parameters provided by the information carried by the SS block.

-440: the accuracy of the information providing the time index is determined based on an error detection code associated with the received system information.

In an embodiment, the error detection code may be a CRC attachment of information bits corresponding to the received system information. In these embodiments, determining 440 the accuracy of the information providing the time index may include:

-performing a CRC of the received system information based on a CRC attachment,

-when the performed CRC indicates erroneously received system information, determining that the information providing the time index is not accurate, and

-determining that the information providing the time index is accurate when the performed CRC indicates correctly received system information.

The method may further comprise: based on the determined accuracy of the information providing the time index, it is determined 450 how to perform the initial access procedure. Determining 450 how to perform the initial access procedure may further comprise:

-completing an initial access procedure based on the received system information when the information providing the time index is determined to be accurate,

-detecting another SS block to receive the system information and the time index before completing the initial access procedure when the information providing the time index is determined to be inaccurate.

In an embodiment, the method further comprises: synchronization with the network node is acquired based on information in the SS block.

The method may further comprise: information providing a time index is used to determine where the boundary of the set of SS bursts is or where the set of SS bursts begins.

In an embodiment, system information is received based on a boundary of a set of SS bursts indicated by a time index.

Embodiments of the apparatus described with reference to FIGS. 5-6

An embodiment of a network node 500 of a wireless communication network is illustrated in the block diagram of fig. 5, the network node 500 being configured to transmit system information to a wireless device in an SS block of a set of SS bursts comprising at least one synchronization signal SS block. In an embodiment, the network node is a gNodeB. The system information is multiplexed with information that provides a time index that indicates which SS block of the set of SS bursts is being transmitted. The network node is further configured to scramble system information using a scrambling sequence generated based on the information providing the time index and transmit the scrambled system information multiplexed with the information providing the time index of the SS block to the wireless device, wherein the error detection code is related to the system information.

In an embodiment, the network node is further configured to scramble the system information by scrambling coded bits of the system information. The error detection code may be a cyclic redundancy check, CRC, attachment to the information bits corresponding to the system information.

The network node may be configured to transmit information providing the time index without any associated error detection codes. The network node may be further configured to generate the scrambling sequence by initializing the scrambling sequence at the beginning of the SS block. In an embodiment, the scrambling sequence is a pseudo-random sequence, and the network node may be further configured to generate the pseudo-random sequence based on an identification of a cell (cell ID) associated with the SS block.

As illustrated in fig. 5, the network node 500 may comprise at least one processing circuit 510 and optionally may also comprise a memory 530. In an embodiment, the memory 530 may be placed in some other node or unit, or may be placed at least separately from the network node. The network node may also include one or more input/output (I/O) units 520 configured to communicate with the wireless device or another network node. In an embodiment, an input/output (I/O) unit 520 may include: a transceiver connected to one or more antennas through an antenna port for wireless communication with wireless devices in the network, and/or interface circuitry adapted for communication with other network nodes over various interfaces. The memory 530 may contain instructions executable by the at least one processing circuit 510 whereby the network node may be configured to perform the method described herein, for example with reference to fig. 3.

In yet another embodiment, illustrated in fig. 5, the network node may comprise a generating module 511, a scrambling module 512 and a transmitting module 513, which are adapted to perform the method steps illustrated in fig. 3, respectively.

The network node may comprise further modules adapted to perform any of the methods previously described herein.

The modules described above are functional units that may be implemented in hardware, software, firmware, or any combination thereof. In one embodiment, the modules are implemented as computer programs running on at least one processing circuit 510.

In yet another alternative way of describing the embodiment in fig. 5, the network node may comprise a Central Processing Unit (CPU), which may be a single unit or a plurality of units. Furthermore, the network node may comprise at least one Computer Program Product (CPP) with a computer-readable medium 541, the computer-readable medium 541 being for example in the form of a non-volatile memory, for example an EEPROM (electrically erasable programmable read only memory), a flash memory or a disk drive. The CPP may comprise a computer program 540 stored on a computer readable medium 541, the computer program 540 comprising code means which, when run on the CPU of the network node, causes the network node to perform the method described earlier in connection with fig. 3. In other words, the code means correspond to the at least one processing circuit 510 of the network node in fig. 5, when they are run on the CPU.

An embodiment of a wireless device 600 is schematically illustrated in the block diagram of fig. 6. The wireless device 600 is configured to receive system information from a network node of a wireless communication system, the system information being received in an SS block of a set of SS bursts comprising at least one synchronization signal SS block. In an embodiment, the wireless device is a UE. The system information is multiplexed with information that provides a time index that indicates which SS block of the set of SS bursts is being received. The wireless device is further configured to: the method includes receiving information providing a time index, receiving system information by descrambling the system information using a scrambling sequence generated based on the information providing the time index, and determining accuracy of the information providing the time index based on an error detection code associated with the received system information.

In an embodiment, the error detection code is a cyclic redundancy check, CRC, attachment to information bits corresponding to the received system information, and the wireless device is further configured to determine the accuracy of the information providing the time index by:

-performing a CRC of the received system information based on a CRC attachment,

The wireless device may be further configured to: based on the determined accuracy of the information providing the time index, it is determined how to perform the initial access procedure.

In an embodiment, the wireless device is further configured to determine how to perform the initial access procedure by:

-when the information providing the time index is determined to be accurate, completing an initial access procedure based on the received system information, and

In an embodiment, the wireless device is further configured to acquire synchronization with the network node based on information in the SS block.

The wireless device may be further configured to descramble the system information by descrambling the encoded bits of the system information.

The wireless device may be further configured to receive information providing the time index without any associated error detection codes.

In an embodiment, the wireless device is further configured to generate the scrambling sequence by initializing the scrambling sequence at the beginning of the SS block.

The wireless device may be further configured to use the information providing the time index to determine where the boundary of the set of SS bursts is or where the set of SS bursts begins.

The wireless device may be further configured to receive system information based on the boundary of the set of SS bursts indicated by the time index.

In an embodiment, the scrambling sequence is a pseudo-random sequence, and the wireless device is configured to generate the pseudo-random sequence based on an identification of a cell (cell ID) associated with the SS block.

As illustrated in fig. 6, wireless device 600 may include at least one processing circuit 610 and optionally may also include memory 630. In an embodiment, memory 630 may be located in some other node or unit, or may be located at least separately from wireless device 600. Wireless device 600 may also include one or more input/output (I/O) units 620 configured to communicate with a network node, such as a gnnodeb. In an embodiment, the input/output (I/O) unit 620 may include a transceiver connected to one or more antennas through an antenna port to wirelessly communicate with network nodes in a network. Memory 630 may contain instructions executable by the at least one processing circuit 610 whereby wireless device 600 may be configured to perform any of the methods previously described herein, e.g., with reference to fig. 4.

In yet another embodiment, illustrated in fig. 6, the wireless device 600 may comprise a first receiving module 611, a generating module 612, a second receiving module 613 and a determining module 614, which are adapted to perform the method steps of fig. 4, respectively.

Wireless device 600 may include additional modules adapted to perform any of the methods previously described herein. The modules described above are functional units that may be implemented in hardware, software, firmware, or any combination thereof. In one embodiment, the modules are implemented as computer programs running on at least one processing circuit 610.

In yet another alternative manner of describing the embodiment in fig. 6, wireless device 600 may include a Central Processing Unit (CPU), which may be a single unit or multiple units. Further, the wireless device 600 may include at least one Computer Program Product (CPP) having a computer-readable medium 641, for example in the form of a non-volatile memory, such as an EEPROM (electrically erasable programmable read only memory), a flash memory, or a disk drive. The CPP may comprise a computer program 640 stored on a computer readable medium 641, the computer program 640 comprising code means which, when run on the CPU of the wireless device 600, causes the wireless device 600 to perform the method described earlier in connection with fig. 4. In other words, the code means correspond to the at least one processing circuit 610 of the wireless device 600 in fig. 6, when they are run on the CPU.

The invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims.

List of further exemplary embodiments

E1. A method performed by a network node of a wireless communication network for transmitting system information to a wireless device in SS blocks of an SS burst comprising at least one synchronization signal, SS, block, wherein the system information is multiplexed with information providing a time index indicating a boundary of the SS burst or set of SS bursts, the method comprising:

-generating (310) a scrambling sequence based on information providing a time index,

-scrambling (320) system information using the generated scrambling sequence,

-transmitting (330) the scrambled system information multiplexed with the information providing the time index to the wireless device in an SS block.

E2. The method of embodiment E1 wherein scrambling (320) system information includes at least one of:

-scrambling error detection code bits associated with system information;

-scrambling encoded bits of system information;

-scrambling the modulated symbols of the system information.

E3. The method according to any of the preceding embodiments, wherein the information providing the time index is transmitted without any error detection code.

E4. The method according to any of the preceding embodiments, wherein the scrambling sequence is a pseudo-random sequence whose initialization value depends on the time index.

E5. The method of embodiment E4 wherein the initialization value is dependent on additional parameters provided by information carried by the SS block.

E6. A method performed by a wireless device for receiving system information from a network node of a wireless communication system, the system information being received in SS blocks of an SS burst comprising at least one synchronization signal, SS, block, wherein the system information is multiplexed with information providing a time index indicating a boundary of the SS burst or set of SS bursts, the method comprising:

-receiving (410) information providing a time index,

-generating (420) a scrambling sequence based on information providing a time index,

-receiving (430) system information based on a boundary of an SS burst or set of SS bursts, indicated by a time index, wherein the receiving comprises descrambling the received system information using the generated scrambling sequence,

-determining (440) an accuracy of the information providing the time index based on an error detection code associated with the system information.

E7. The method of embodiment E6, further comprising:

-initiating an initial access procedure based on the received system information when the information providing the time index is determined to be accurate,

-detecting another SS block to receive system information when the information providing the time index is determined to be inaccurate.

E8. The method as in any one of embodiments E6-E7, wherein descrambling received system information comprises at least one of:

-descrambling error detection code bits associated with system information;

-descrambling encoded bits of system information;

-descrambling the modulated symbols of the system information.

E9. The method as in any one of embodiments E6-E8 wherein the information providing the time index is received without any error detection codes.

E10. The method as in any one of embodiments E6-E9, wherein the scrambling sequence is a pseudo-random sequence whose initialization value depends on the time index.

E11. The method of embodiment E10 wherein the initialization value is dependent on additional parameters provided by information carried by the SS block.

E12. A network node (500) of a wireless communication network configured to transmit system information to a wireless device in SS blocks of an SS burst comprising at least one synchronization signal, SS, block, wherein the system information is multiplexed with information providing a time index indicating a boundary of the SS burst or set of SS bursts, the network node further configured to:

-generating a scrambling sequence based on information providing a time index,

scrambling system information using the generated scrambling sequence,

-transmitting the scrambled system information multiplexed with the information providing the time index to the wireless device in the SS block.

E13. The network node according to embodiment E12, configured to scramble system information in at least one of the following ways:

-scrambling error detection code bits associated with system information;

-scrambling encoded bits of system information;

-scrambling the modulated symbols of the system information.

E14. The network node of any of embodiments E12-E13, wherein the information providing the time index is transmitted without any error detection codes.

E15. The network node of any of embodiments E12-E14, wherein the scrambling sequence is a pseudo-random sequence whose initialization value depends on the time index.

E16. The network node according to embodiment E15, wherein the initialization value depends on further parameters provided by information carried by the SS block.

E17. A wireless device (600) configured to receive system information from a network node of a wireless communication system, the system information being received in SS blocks of an SS burst comprising at least one synchronization signal, SS, block, wherein the system information is multiplexed with information providing a time index indicating a boundary of the SS burst or of a set of SS bursts, the wireless device further configured to:

-receiving information providing a time index,

-generating a scrambling sequence based on information providing a time index,

-receiving system information based on a boundary of an SS burst or set of SS bursts indicated by a time index, wherein the receiving comprises descrambling the received system information using the generated scrambling sequence,

-determining the accuracy of the information providing the time index based on an error detection code associated with the system information.

E18. The wireless device of embodiment E17, further configured to:

E19. The wireless device of any of embodiments E17-E18, being further configured to descramble received system information in at least one of the following ways:

-descrambling error detection code bits associated with system information;

-descrambling encoded bits of system information;

-descrambling the modulated symbols of the system information.

E20. The wireless device as in any of embodiments E17-E19, wherein the information providing the time index is received without any error detection codes.

E21. The wireless device as in any of embodiments E17-E20, wherein the scrambling sequence is a pseudo-random sequence whose initialization value depends on the time index.

E22. The wireless device of embodiment E21, wherein the initialization value is dependent on further parameters provided by information carried by the SS block.

E23. A network node (500) of a wireless communication network, configured to transmit system information to a wireless device in SS blocks of an SS burst comprising at least one synchronization signal, SS, block, wherein the system information is multiplexed with information providing a time index indicating a boundary of the SS burst or set of SS bursts, the network node comprising processing circuitry (510) and a memory (530), the memory comprising instructions executable by the processing circuitry, whereby the network node is configured to:

-generating a scrambling sequence based on information providing a time index,

scrambling system information using the generated scrambling sequence,

E24. The network node of embodiment E23, wherein the memory contains instructions executable by the processing circuit, whereby the network node is configured to perform the method of any of embodiments E2-E5.

E25. A wireless device (600) configured to receive system information from a network node of a wireless communication system, the system information being received in SS blocks of an SS burst comprising at least one synchronization signal, SS, block, wherein the system information is multiplexed with information providing a time index indicating a boundary of the SS burst or set of SS bursts, the wireless device comprising processing circuitry (610) and a memory (630), the memory containing instructions executable by the processing circuitry, whereby the wireless device is configured to:

-receiving information providing a time index,

-generating a scrambling sequence based on information providing a time index,

E26. The wireless device of embodiment E25, wherein the memory contains instructions executable by the processing circuit, whereby the wireless device is configured to perform the method of any of embodiments E7-E11.

E27. A network node (500) of a wireless communication network configured to transmit system information to a wireless device in SS blocks of an SS burst comprising at least one synchronization signal, SS, block, wherein the system information is multiplexed with information providing a time index indicating a boundary of the SS burst or set of SS bursts, the network node comprising:

a generation module (511) adapted to generate a scrambling sequence based on information providing a time index,

a scrambling module (512) adapted to scramble system information using the generated scrambling sequence,

-a transmitting module (513) adapted to transmit the scrambled system information multiplexed with the information providing the time index to the wireless device in an SS block.

E28. The network node of embodiment E27, further comprising modules adapted to perform the methods of any of embodiments E2-E5.

E29. A wireless device (600) configured to receive system information from a network node of a wireless communication system, the system information being received in SS blocks of an SS burst comprising at least one synchronization signal, SS, block, wherein the system information is multiplexed with information providing a time index indicating a boundary of the SS burst or a set of SS bursts, the wireless device comprising:

a first receiving module (611) adapted to receive information providing a time index,

a generation module (612) adapted to generate a scrambling sequence based on information providing a time index,

-a second receiving module (613) adapted to receive system information based on a boundary of an SS burst or set of SS bursts indicated by a time index, wherein the receiving comprises descrambling the received system information using the generated scrambling sequence,

-a determining module (614) adapted to determine an accuracy of the information providing the time index based on an error detection code associated with the system information.

E30. The wireless device of embodiment E29, further comprising modules adapted to perform the method of any of embodiments E7-E11.

E31. A computer program comprising instructions which, when executed by at least one processor of a network node, cause the network node to perform the method of any of embodiments E1-E5.

E32. A computer program comprising instructions which, when executed by at least one processor of a wireless device, cause the wireless device to perform the method of any of embodiments E6-E11.

E33. A carrier containing the computer program of embodiment E31 or E32, wherein the carrier is one of: an electronic signal, an optical signal, a radio signal, or a computer-readable storage medium.

Claims

1. A method performed by a wireless device for receiving system information from a network node of a wireless communication system, the system information being received in an SS block of a set of SS bursts comprising at least one synchronization signal, SS, block, wherein the system information is multiplexed with information providing a time index indicating which SS block of the set of SS bursts is being received, the method comprising:

-receiving (410) the information providing the time index,

-receiving (430) the system information, wherein receiving (430) comprises descrambling the system information using a scrambling sequence generated (420) based on the information providing the time index,

-determining (440) an accuracy of the information providing the time index based on an error detection code associated with the received system information.

2. The method of claim 1, wherein the error detection code is a cyclic redundancy check, CRC, attachment to information bits corresponding to the received system information, and wherein determining (440) the accuracy of the information providing the time index comprises:

-performing a CRC of the received system information based on the CRC attachment,

-determining that the information providing the time index is inaccurate when the performed CRC indicates erroneously received system information, an

3. The method according to any of the preceding claims, further comprising:

-determining (450) how to perform an initial access procedure based on the determined accuracy of the information providing the time index.

4. The method of claim 3, wherein determining (450) how to perform an initial access procedure comprises:

-completing the initial access procedure based on the received system information when the information providing the time index is determined to be accurate,

-detecting another SS block to receive system information and a time index before completing the initial access procedure when the information providing the time index is determined to be inaccurate.

5. The method according to any of claims 1-2, wherein the information providing the time index is received without any associated error detection code.

6. The method of any of claims 1-2, wherein generating (420) the scrambling sequence comprises initializing the scrambling sequence at a beginning of the SS block.

7. The method according to any one of claims 1-2, further comprising: using the information providing the time index to determine where a boundary of the set of SS bursts is or where the set of SS bursts begins.

8. The method of any of claims 1-2, wherein the system information is received based on a boundary of the set of SS bursts indicated by the time index.

9. A method performed by a network node of a wireless communication network for transmitting system information to a wireless device in an SS block of a set of SS bursts comprising at least one synchronization signal, SS, block, wherein the system information is multiplexed with information providing a time index indicating which SS block of the set of SS bursts is being transmitted, the method comprising:

-scrambling (320) the system information using a scrambling sequence generated (310) based on the information providing the time index,

-transmitting (330), to the wireless device, scrambled system information multiplexed with information providing the time index of the SS block, wherein an error detection code is related to the system information.

10. The method of claim 9, wherein scrambling (320) the system information comprises scrambling coded bits of the system information.

11. The method according to any of claims 9-10, wherein the error detection code is a cyclic redundancy check, CRC, attachment to information bits corresponding to the system information.

12. The method according to any of claims 9-10, wherein the information providing the time index is transmitted without any associated error detection code.

13. The method of any of claims 9-10, wherein generating (310) the scrambling sequence comprises initializing the scrambling sequence at a beginning of the SS block.

14. A computer-readable medium for a wireless device (600) to receive system information from a network node of a wireless communication system, the system information being received in an SS block of a set of SS bursts comprising at least one synchronization signal, SS, block, wherein the system information is multiplexed with information providing a time index indicating which SS block of the set of SS bursts is being received, wherein the computer-readable medium has stored instructions that, when executed by a processor of the wireless device, cause the wireless device to:

-receiving said information providing said time index,

-receiving the system information by descrambling the system information using a scrambling sequence generated based on the information providing the time index,

-determining the accuracy of the information providing the time index based on an error detection code associated with the received system information.

15. The computer-readable medium of claim 14, wherein the instructions, when executed by the processor, further cause the wireless device to perform the method of any of claims 2-8.

16. A computer-readable medium for a network node (500) of a wireless communication network to transmit system information to a wireless device in SS blocks of a set of SS bursts comprising at least one synchronization signal, SS, block, wherein the system information is multiplexed with information providing a time index indicating which SS block of the set of SS bursts is being transmitted, wherein the computer-readable medium has stored instructions that, when executed by a processor of the network node, cause the network node to:

-scrambling the system information using a scrambling sequence generated based on the information providing the time index, an

-transmitting, to the wireless device, scrambled system information multiplexed with information providing the time index of the SS block, wherein an error detection code is associated with the system information.

17. The computer-readable medium of claim 16, wherein the instructions, when executed by the processor, further cause the network node to perform the method of any of claims 10-13.

18. A wireless device (600) for receiving system information from a network node of a wireless communication system, the system information being received in SS blocks of a set of SS bursts comprising at least one synchronization signal, SS, block, wherein the system information is multiplexed with information providing a time index indicating which SS block of the set of SS bursts is being received, the wireless device comprising processing circuitry (610) and memory (630), the memory containing instructions executable by the processing circuitry, which instructions, when executed by the processing circuitry, cause the wireless device to:

-receiving said information providing said time index,

19. The wireless device of claim 18, wherein the instructions, when executed by the processing circuit, further cause the wireless device to perform the method of any of claims 2-8.

20. A network node (500) of a wireless communication network for transmitting system information to a wireless device in SS blocks of a set of SS bursts comprising at least one synchronization signal, SS, block, wherein the system information is multiplexed with information providing a time index indicating which SS block of the set of SS bursts is being transmitted, the network node comprising processing circuitry (510) and a memory (530), the memory containing instructions executable by the processing circuitry, which instructions, when executed by the processing circuitry, cause the network node to:

21. The network node of claim 20, wherein the instructions, when executed by the processing circuit, further cause the network node to perform the method of any of claims 10-13.